Process of preparing pigments fast to light



Patented May 24, 1932 UNITED STATES PATENT OFFICE KARL GERBEL, OF WIESDORF-ON-THERHINE, GERMANY, ASSIGNOR TO GENERAL ANILINE WORKS, INQ, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE PROCESS OF PREPARING PIGMENTS FAST TO LIGHT No Drawing. Application filed March 8, 1929, Serial No. 345,585, and in Germany March 7, 1928.

The presentinvention relates to pigments fast to light and the process of preparing the same.

In U. S. Patent No.-1,731,081 there is described a process of preparing reduction products from molybdenum phosphotungstlc acids of the general formula:

wherein it stands for one of the numbers 18 and 24:. The process of preparing the starting material, that is, the compounds is described in Journal of Biological Chemistry, 1920, volume 43. In the above cited patent there is further stated that the reduced complex molybdenum phosphotungstic aclds are suitable for the manufacture of pigments.

Now I have found that the fastness to light of the pigments can be highly increased by boiling in an aqueous suspension the pigment after precipitating the dyestuff with the reduced complex compound. For the purpose of my invention there are suitable dyestuffs, containing at least one amino group, such as acid dyestufis, containing at least one ammo group and basic dyestuffs. The process is carried out by preparing a substratum for p1gment dyestuffs according to usual methods as described in the literature, for example, in Chemie in Einzeldarstellungen, edited by J. Schmidt, volume XIII: Die Korperfarben von Hans Wagner, page 3133l9; VVissenschaftliche Verlagsgesellschaft, m. b. H., Stuttgart, 1928. The substratum, obtained according to one of the known processes, may be washed, if desired, and thereafter there is added the aqueous solution of a basic dyestuff to the substratum and then the required quantity of the molybdenum phosphotungstic acid whereby the dyestuff is precipitated on the substratum to form a pigment. If an acid dyestuf'f containing one or more aminogroups, is used, the aqueous solution of the dyestufi is added to the substratum, then the required quantity of the complex compound and is added, and finally the molybdenum phosphotungstic-acid complex compound is precipitated by the addition of a'precipitating agent, such as barium chloride. Otherwise an aqueous mixture of the dyestuff and the reduced complex compound is added to the substratum and precipitated by the addition of a precipitating agent.

' The quantity of the reduced molybdenum pliosphotungstic complex compound varies somewhat with the specific dyestuff used, but generally one to three timesthe quantity, calculated on the amount of the dyestufi, will be sufficient; generally two parts by weight are added.

The pigments thus obtained are then boiled in aqueous suspension for a prolonged time, say'one-half to two hours, whereby their fastness to'light is highly increased.

The invention is illustrated by the following examples, without being limited there to Example 1.--15 parts by weight of aluminium sulfate containing 18% of Al O dissolved in 150 parts of water, are mixed with 7 .5 parts by weight of calcined soda dissolved in 7 5 parts by weight of water. To the precipitate, after previously washing the same by decanting, are added 1.5 parts by weight of methylviolet 1 B (compare Schultz,

Farbstofitabellen 1923, volume 1, page 167 No. 51 5) in an aqueous solution and 3 parts by weight of the above identified reduced complex molybdenum phosphotungstic compound of the formula:

dissolved in 30 parts by weight of water. The pigment thus obtained in anaqueous suspension'is boiled for about 2 hours and filtered after cooling.

Ewample 2.5.5 parts by weight of aluminium sulfate containing 18% of A1 0 dissolved in parts by weight of water, 3.6 parts by weight of sodium phosphate dissolved in 36 parts by weight of water, and 1.6'parts by weight of calcined soda dissolved in 16 parts by weight of water, are mixed together. The substratum thus obtained is washed three times by decanting, then there are added to the precipitate 1 part by weight Rhodamin B extra (compare, Schultz, Farbstofftabellen 1923, volume 1, page 192, N0. 573) dissolved in 10 parts by weight of water and two parts by weight of the reduced complex coiiipouiid of the formula:

18 (WO +M0O )P O .3H O dissolved in 20 parts by weight of water. The pigment thus obtained is boiled'in the aqueous suspension for about2 hours and filtered after cooling. 7 o v E mample 3.-5 parts by weight of aluminium siilfatecontai-nin'g 18% "of A1 0 "dissolved in parts by weight of water are I iiii't'e'd "with 2.5"p'arts by weight of calcined soda dissolyedin 25p'arts by weight ofwate'r. To he percipitation '1 mixture there are added 1 part weiglitjof jacidfg'reen GG extra (compar Schultz, Farbstoift'abell'en, Volume 1,1page1 60, No. 505) dissolved in 10'pai1ts by weightbf water, 1.5? parts by weight'of th'e reduced complex compound ofthe'formula:

24(WVO +MoOg)-P Og.3HgO di'sso'lyed ini151partsof water and 7 parts vight urban-um chloride. Thepigment thus obtained "1's boiled "in the "aqueous "suspnsin f'ofabout 1 houra'n'd filtere'dafter cooling.

1. rhe proee'ss' of prepaiing' pigments fast to li'g'iit whi'ch comprises boiling for about to 2 hours the aqueous suspension ofa pigment which has been 'l'pre'pared from a dythfi "containing 'at least one "amind'group, substratum, for pigment dyestufis, and about l'to 3'times the [weight'ofthe dyestii'ff of a reduction product from" molybdemm pl'i'o'sphotungstic acids of tl'1e"general formula:

'nfW'O +MoO PO :3H O wheifein n" sta'n ds for one of the "numbers 18 was 2. The pr'oces's'of' repa in pignients'fast to light which "comprises boiling for "about to' 2 lioursthe aqueous 'suspensionbfa pigment "which has been prepared from "a dyestuif containing at least one amino group, a substratum -fo'r :piginent dyestuffs, and about twice the weight of the dyestuff of a reduction product from f the molybdenum pho'spliot'u'fig'stic acid of the formula:

3. The process of preparingpigmentsfast to light which comprises addino to a f 'substi-awmg hich has been. prepared according to one the well knownprocesses, an aqueous solution of a dyestuff containing at least "eile fmine grou and' abdut lito times the ht Of the Ely-saunashesitation prodjii t '1b'm"molybdeiiiiinphosphotfifigstic'acids of the-general formula:

9% (W0 M00 P 0 311 0 wherein n stands for one of the numbers 18 and 24, and boiling the aqueous suspension of the pigments, thus obtained, for about to 2 hours. L

The proce'ss' f preparing pigments fast to light which comprises adding to a subsu-ammwhich has been prepared according to one of the'well knowntproeessesan aqueoussulutio'h o'f a dyestutf' 'containin'g at least one amino group, and about 1 to 3 times the weight of th edyestulfof a reduction product from molybdenum phosphotungstic acids of the general "ferret-11a:

-nwo-a eareogyrgoaiaio 6 The process ofpreparingpigments fast to light which comprises adding to a substratum, which 1158"bGfBIlJPIQPQ1Bd by-m ixin g;the;aq-ueous; solutions of -15 ;part s by of A1 0 and -7-.5p arts by weight-of calcined soda, 1.5 parts by weight of water and -3 partsb'y'weig-ht of a reduction. productfrom the molybdenumrphosphotungstic acid of the formula:

"24; (V0 MoOgfiPgO- fififi o boiling the aqueous -suspensien -'of the pigment, thus obtained-, for about 2 hours.

7. As new artjitles -of- 'manufae'tuie,lake pigments fast to light; prepared by thetprocess 'as "claimed claim 1. I

In testimony whereofl liave-*liereunto set myhad.

KARLGERBEL. [-ns] 

